In recent year, a parametric speaker with high directivity to propagate sound to a person at a particular position is getting attention. It is expected to mount the parametric speaker on an electronic device, for example, a mobile phone, etc., and is expected to be used for propagating a sound signal around a user, etc.
Here, when the parametric speaker is mounted on the electronic device, for example, a mobile phone, etc., it is desired to miniaturize the parametric speaker. However, it is difficult to miniaturize an electro-dynamic electroacoustic transducer in its principle. Therefore, it is expected to use an electroacoustic transducer using a piezoelectric vibrator.
Patent Literature 1 discloses an electroacoustic transducer comprising a piezoelectric vibrator, and being enabled to use in broadband including a low frequency band.    [Patent Literature 1]    Japanese Patent Kokai Publication No. 2006-246279A